/*=====================================================================*
 *                   Copyright (C) 2011 Paul Mineiro                   *
 * All rights reserved.                                                *
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 * Redistribution and use in source and binary forms, with             *
 * or without modification, are permitted provided that the            *
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 *     above copyright notice, this list of conditions and             *
 *     the following disclaimer.                                       *
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 *     * Redistributions in binary form must reproduce the             *
 *     above copyright notice, this list of conditions and             *
 *     the following disclaimer in the documentation and/or            *
 *     other materials provided with the distribution.                 *
 *                                                                     *
 *     * Neither the name of Paul Mineiro nor the names                *
 *     of other contributors may be used to endorse or promote         *
 *     products derived from this software without specific            *
 *     prior written permission.                                       *
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND              *
 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,         *
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES               *
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE             *
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER               *
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 * Contact: Paul Mineiro <paul@mineiro.com>                            *
 *=====================================================================*/

#include "em.h"
#include "estep.h"
#include "mstep.h"

#include <math.h>

float
em (const float*                     alpha,
    unsigned int                     n_labels,
    float*                           logbeta,
    float*                           pz,
    const float*                     logpriorz,
    int                              clamp,
    const Rating*                    ratings,
    unsigned int                     n_ratings,
    const Distribution*              priorlogbeta,
    int                              symmetric,
    unsigned int                     maxiter,
    float                            tol)
{
  *logbeta = 0;
  float hq = estep (alpha, n_labels, *logbeta, pz, logpriorz,
                    clamp, ratings, n_ratings, symmetric);

  float q = mstep (alpha, n_labels, logbeta, pz, logpriorz,
                   ratings, n_ratings, priorlogbeta, symmetric, hq, 20, tol);
  float lastq = q;
  unsigned int iter = 0;

  do
    {
      hq = estep (alpha, n_labels, *logbeta, pz, logpriorz,
                  clamp, ratings, n_ratings, symmetric);
      q = mstep (alpha, n_labels, logbeta, pz, logpriorz,
                 ratings, n_ratings, priorlogbeta, symmetric, hq, 20, tol);
    }
  while (fabs (q - lastq) > tol * (fabs (q) + fabs (lastq)) &&
         ++iter < maxiter);

  return q;
}
